Re: [PATCH 7/7] [v2] drivers/misc: introduce Freescale hypervisor management driver

On Wednesday 01 June 2011, Timur Tabi wrote:

The Freescale hypervisor management driver provides several services to
drivers and applications related to the Freescale hypervisor:

1. An ioctl interface for querying and managing partitions

2. A file interface to reading incoming doorbells

3. An interrupt handler for shutting down the partition upon receiving the
   shutdown doorbell from a manager partition

4. An interface for receiving callbacks when a managed partition shuts down.

Signed-off-by: Timur Tabi <redacted>
---
 drivers/misc/Kconfig           |    7 +
 drivers/misc/Makefile          |    1 +
 drivers/misc/fsl_hypervisor.c  |  941 ++++++++++++++++++++++++++++++++++++++++
 include/linux/Kbuild           |    1 +
 include/linux/fsl_hypervisor.h |  203 +++++++++
 5 files changed, 1153 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/fsl_hypervisor.c
 create mode 100644 include/linux/fsl_hypervisor.h

I think drivers/misc is not the right place for this, but I'm not completely
sure what is. drivers/firmware would be better at least, but virt/fsl might
also be ok.

+static long ioctl_dtprop(struct fsl_hv_ioctl_prop __user *p, int set)
+{
+	struct fsl_hv_ioctl_prop param;
+	char __user *upath, *upropname;
+	void __user *upropval;
+	char *path = NULL, *propname = NULL;
+	void *propval = NULL;
+	int ret = 0;
+

I'm not convinced that an ioctl interface is the right way to work with
device tree properties. A more natural way would be to export it as
a file system, or maybe as a flattened device tree blob (the latter option
would require changing the hypervisor interface, which might not be
possible).

+/**
+ * fsl_hv_ioctl: ioctl main entry point
+ */
+static long fsl_hv_ioctl(struct file *file, unsigned int cmd,
+			 unsigned long argaddr)
+{
+	union fsl_hv_ioctl_param __user *arg =
+		(union fsl_hv_ioctl_param __user *)argaddr;
+	long ret;
+

For an ioctl, please follow the normal pattern of defining a separate
structure for each case, no union.

You can use a void __user * in the common ioctl function, and pass that
to the typed argument list in the specific functions.

	Arnd